This was the third and last spacecraft prepared for a Venus encounter by the Soviets in 1965. All three spacecraft had originally been intended for Mars exploration in 1964 and 1965.
In this case, during coast to Earth orbit, a combustion chamber in the booster’s third stage engine exploded due to a crack in the fuel pipeline. Although the payload reached Earth orbit, the Blok L upper stage was tumbling and was unable to fire for trans-Venus trajectory injection.
The probe remained stranded in Earth orbit and the Soviets named it Kosmos 96 to disguise its true mission. The probe decayed on Dec. 9, 1965.
Siddiqi, Asif A. Beyond Earth: A Chronicle of Deep Space Exploration, 1958-2016. NASA History Program Office, 2018.